Oprah Winfrey said today that disgraced cyclist Lance Armstrong came well prepared for their highly anticipated interview, although he "did not come clean in the manner [she] expected."

Winfrey, who discussed the interview on "CBS This Morning" today, said, "We were mesmerized and riveted by some of his answers. I feel that he answered the questions in a way that he was ready. … He certainly had prepared himself for this moment. … He brought it. He really did."

Armstrong had apologized to staffers at the Livestrong Foundation before the Monday interview with Winfrey at a hotel in Austin, Texas, and reportedly admitted to them that he used performance-enhancing drugs throughout his storied career.

Armstrong also confessed to Winfrey to using the drugs, sources have told ABC News. Winfrey said this morning that the entire interview, for which she had prepared 112 questions, was difficult.

"I would say there were a couple of times where he was emotional," she said. "But that doesn't describe the intensity at times."

As for the cyclist's sense of remorse, Winfrey said that will be for viewers to decide.
"I would rather people make their own decisions about whether he was contrite or not," she said.

The interview will air on the OWN network for two nights, starting at 9 p.m. ET Thursday and continuing Friday.

Meanwhile, the federal government is likely to join a whistle-blower lawsuit against Armstrong, originally filed by his former cycling teammate Floyd Landis, sources told ABC News.

The government is seeking to recoup millions of dollars from Armstrong after years of his denying that he used performance-enhancing drugs, the sources said. The U.S. Postal Service, which is an independent agency of the federal government, was a longtime sponsor of Armstrong's racing career.

The deadline for the government's potentially joining in the matter was a likely motivation for Armstrong's interview with Winfrey, sources told ABC News.

The lawsuit remains sealed in federal court.

Armstrong is now talking with authorities about possibly paying back some of the Postal Service sponsorship money, a government source told ABC News Monday.

The deadline for the department to join the case is Thursday, the same day Armstrong's much-anticipated interview with Winfrey is set to air.

Armstrong is also talking to authorities about confessing and naming names, giving up others involved in illegal doping. This could result in a reduction of his lifetime ban, according to a source, if Armstrong provides substantial and meaningful information.

As for the Winfrey interview, it was Armstrong's first since officials stripped him of his world cycling titles in response to doping allegations.

Word of Armstrong's admission comes after a Livestrong official said that Armstrong apologized Monday to the foundation's staff ahead of his interview.

The disgraced cyclist gathered with about 100 Livestrong Foundation staffers at their Austin headquarters for a meeting that included social workers who deal directly with patients as part of the group's mission to support cancer victims.

Armstrong's "sincere and heartfelt apology" generated lots of tears, spokeswoman Katherine McLane said, adding that he "took responsibility" for the trouble he has caused the foundation.

McLane declined to say whether Armstrong's comments included an admission of doping, just that the cyclist wanted the staff to hear from him in person rather than rely on second-hand accounts.

Armstrong then took questions from the staff.

Armstrong's story has never changed. In front of cameras, microphones, fans, sponsors, cancer survivors -- even under oath -- Lance Armstrong hasn't just denied ever using performance enhancing drugs, he has done so in an indignant, even threatening way.

Armstrong, 41, was stripped of his seven Tour de France titles and banned from the sport for life by the U.S. Anti-Doping Agency in October 2012, after allegations that he benefited from years of systematic doping, using banned substances and receiving illicit blood transfusions.

"Lance Armstrong has no place in cycling and he deserves to be forgotten in cycling," Pat McQuaid, the president of the International Cycling Union, said at a news conference in Switzerland announcing the decision. "This is a landmark day for cycling."